Planned from the beginning?
You are saying the knew Clinton was unlikely to make it through the primary process and Biden was the intended nominee to begin with?
Doesn’t make much sense since it will piss off Clinton voters, Sanders voters who are already po’d will become even more enraged when they see their chance to defeat (maybe) Clinton ripped away causing them to in effect have to start over. And Biden is hardly untainted with his multiple episodes of inappropriate touching and plagiarism.
I have no idea what will happen of course but if Biden is not “hated” as much as Trump and Clinton at this time it is possibly because not much is known about him by those who would vote in a general election.
I think that is what Obama intends. The last thing Obama wants is for the Clintons to win. That will shut him out of any influence in the party. By backing Biden as the defacto nominee, he knows there is no way Biden could win. That leaves Obama as the main influence of the party when he leaves office. Obama is for Obama.